Sachets which contain detergent powder and which can deliver detergent ingredients in washing machines in a sequential manner, have been disclosed in the prior art.
EP 132 726 (Henkel) relates to a sachet within a sachet, whereby the inner sachet consists of material which is water-soluble at a predetermined temperature, and whereby the outer sachet also contains a cleaning composition. U.S. Pat. No. 4,155,292 (Procter) relates to a sachet within a sachet for machine dishwashing, whereby the inner watersoluble bag is filled with enzyme material, and the outer water-soluble sachet is filled with detergent material. It is, further, disclosed by this document that the release and the stability of the enzyme are controlled.
EP 236 136A (Unilever) discloses a sachet of water permeable material comprising at least 2 compartments of which the first compartment is capable of releasing its contents, within 3 minutes and the second compartment is designed such that release of its contents is delayed for at least 5 minutes from the start of the wash process. From the examples it is clear that this sachet is only suitable for one single washing cycle.
Solid detergent briquettes containing components which raise the solubility have also been disclosed in the prior art, for instance in EP 203 523 A (Henkel).
It is an object of the present invention to provide a sachet containing a detergent composition which sachet is designed such that when used in a washing machine the delivery of the detergent product into the wash liquor is maintained at a constant level during an extended period of machine operating time.
It is a further object of the invention to provide a detergent containing sachet which is suitable for single tank reuse machines such that during consecutive washing cycles the concentration of the detergent product in the wash liquor is maintained at a constant level.
It is a still further object of the invention that this constant level of detergent product is maintained during at least 15 consecutive washing cycles. It is another object of the invention that this detergent containing sachet can be simply prepared.
We have now surprisingly found that a constant delivery of detergent product can be obtained if the sachet contains both detergent powder and solid detergent briquettes. In this context, briquettes are defined as solid detergent blocks which include several discretely shaped detergent particles such as tablets, cubes, etc.